Paul Krugman returned to the debate with me about federal spending in his New York Times column yesterday. He says that federal spending cannot be brought back from its current high levels to the 19 to 20 percent range as a share of GDP, which we saw as recently as 2007. His argument consists of two points.

He declares that military spending as a share of GDP cannot go down. Why? Because, he says, “Republicans, needless to say, oppose.” But as I wrote when he first made this point, defense spending as a share of GDP can come down. And it could come down by an especially large amount as the size of GDP increases with higher economic growth. Krugman is taking defense off the table, not me, and not Republicans who are part of the budget debate in Washington. And he does not mention economic growth.

Krugman also points out that the number of retirees is projected to grow at a more rapid rate than the number of workers paying taxes. This point should not come as a surprise to anyone. But the implication is not that we should tax working people more. Rather the implication is that we should insist that programs like Medicare be reformed to improve their efficiency and deliver improved outcomes for future retirees for each tax dollar spent.

There is a good reform plan on the table which does just this. It would bring federal spending as a share of GDP to the 19-20 percent range and it would improve health care for Medicare recipients; it is none other than the House Budget Resolution of 2012; yes, the Ryan plan. Like the Obama Administration’s proposal, it aims to bring down the growth rate of future Medicare spending from the unsustainable levels under current law. Indeed, depending on economic projections, the Obama Administration’s new plan (presented by President Obama on April 13) proposes to bring the growth rate of future Medicare spending per beneficiary to about the same rate as the House budget plan, which has Medicare payments increasing faster than the CPI as people age.

But by reforming Medicare and thereby avoiding the destructive price controls needed to limit spending in the Administration’s proposal without reform, the House plan would make Medicare recipients relatively better off. The Ryan and Obama plans both propose to reign in the explosive future growth of Medicare spending. The difference is that the Ryan plan does so in a way that is much more beneficial for seniors.